This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 11-245732, filed Aug. 31, 1999, the entire contents of which are incorporated herein by reference.
The present invention relates to an apparatus and method for setting a position of a movable mold of a motor-driven injection molding machine, and particularly to an apparatus and method for setting a position of a movable mold of a motor-driven injection molding machine having a link mechanism for clamping injection molds.
During clamping operation of a stationary mold and a movable mold of the motor-driven injection molding machine, position setting of the movable mold is important. Although this position setting should basically be effected directly on the movable mold, since a servo-motor drives a cross head which is connected to the movable mold via a link mechanism for clamping rather than driving the movable mold directly, the movable mold position is controlled on the basis of the cross head position.
However, because the movable mold and the cross head are connected via a complicated link mechanism, the expression for converting the movable mold position into the cross head position is complicated, and it requires much time to conduct calculation processing thereof.
That is, the operator 1) needs to conduct complicated calculation for converting the movable mold position into the cross head position and 2) necessitates a cumbersome task such as setting the cross head position by actually moving the machine.
In view of the foregoing, it is an object of the invention to provide an apparatus and method for setting a position of a movable mold of a motor-driven injection molding machine which can facilitate position setting concerning clamping operation by simplifying the complicated calculation for converting a movable mold position to a cross head position, and can increase the processing speed.
A position setting apparatus for a movable mold of a motor-driven injection molding machine according to the present invention comprises: means for detecting a position of a first member which is driven by a servo-motor; a memory table in which a correspondence table between position of the first member and position of a second member which is connected to the first member via a link mechanism is preliminarily stored; and means for reading out a position of the second member based on the detected position of the first member with reference to the memory table, wherein position setting of the first member is conducted on the basis of a position error between the read out position of the second member and a target position thereof.
Also, a position setting apparatus for a movable mold of a motor-driven injection molding machine according to the present invention comprises: means for detecting a position of a cross head which is driven by a servo-motor; a memory table in which a correspondence table between position of the cross head and position of a movable mold which is connected to the cross head via a link mechanism is preliminarily stored; and means for reading out a position of the movable mold based on the detected position of the cross head with reference to the memory table; wherein position setting of the cross head is conducted on the basis of a position error between the read out position of the movable mold and a target position thereof.
Also, a position setting method for a movable mold of a motor-driven injection molding machine according to the present invention comprises the steps of: detecting a position of a first member which is driven by a servo-motor; preliminarily storing correspondence between position of the first member and position of a second member which is connected to the first member via a link mechanism in a memory table; reading out a position of the second member based on the detected position of the first member with reference to the memory table; and conducting position setting of the first member on the basis of a position error between the read out position of the second member and a target position thereof.
With these constitutions, it is possible to simplify the complicated calculation for determining the movable mold position from the cross head position and vice versa and facilitate the position setting concerning clamping operation, while increasing the processing speed.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.